1. Field of the Invention
The present invention relates to packaging of radio receiver circuits or devices, particularly communications filters.
2. Discussion of the Known Art
Radio frequency (RF) transceivers for the Joint Tactical Radio System (JTRS) typically have bandpass filters arranged in an intermediate frequency (IF) stage of the transceiver to support the reception and transmission of signal waveforms defined by the JTRS. The waveforms are referred to as being either “narrowband” or “wideband” depending on the bandwidth needed to pass the waveforms through various stages of a transceiver or radio without distortion. Waveforms whose bandwidths are less than 3 MHz wide are generally considered narrowband, and waveforms with bandwidths of 3 MHz or greater are referred to as wideband. Typical uses and bandwidth requirements for several JTRS signal waveforms including WNW, SRW, NCW, HNW, and MUOS are disclosed in T. Mann, JTRS/WIN-T: Networking Waveform Quick Reference Sheets, on the Web at findarticles.com/p/articles/ (Summer 2008), which is incorporated by reference. See also, IT Mentor Group, Inc., Joint Tactical Radio System, on the Web at itmentor.com/jtrs.htm; and Joint Tactical Radio System, at en.wikipedia.org/wiki/JTRS.
Small form factors specified by the military for tactical vehicular radios, as well as cost considerations, tend to limit the number of filters that can be provided with associated switches and matching circuits inside one radio. For example, as shown in FIG. 1, an IF signal stage of a core radio developed by BAE Systems includes a switched bank or array 10 of two surface acoustic wave (SAW) bandpass filters 12, 14, for enabling the bandwidth of the stage to be set to either 0.5 MHz or 1.2 MHz. The filters 12, 14, switches 16, 18, and discrete devices for matching the filters electrically with the IF stage, are arrayed individually over an area of defined length and width on the surface of a circuit board 20. The overall dimensions of the entire core radio meet the Ground Mobile Radio (GMR) form factor specified by the JTRS, but the radio supports only a small subset of the various JTRS waveforms.
Under the JTRS, one GMR platform may operate on up to four communication channels, wherein each channel handles one of the JTRS waveforms (e.g., EPLRS, SINCGARS, HF ISB/SSB/ALE, SRW, WNW, or UHF DAMA SATCOM). See, P. H. Sniffen, Joint Tactical Radio System: AMF, GMR, HMS, on the Web at low-powerwireless.com/blog/designarticles/ (March 2012), which is incorporated by reference.
U.S. Pat. Pub. 2006/0114969 (Jun. 1, 2006) describes a data transmission device including an array of four SAW filters the inputs of which are switched selectively to receive a pulse signal, and the outputs of which are combined to produce analog signals having different frequency characteristics. U.S. Pat. No. 7,460,851 (Dec. 2, 2008) discloses a device for integrating a single SAW filter and a transceiver by encapsulating them to form an integrated chip.
Experience has shown that radios conforming to the GMR form factor are too large and costly to be deployed in some military vehicles including tanks, and fall short of meeting certain design objectives. While satisfying many needs, JTRS signal waveforms such as the Soldier Radio Waveform (SRW) and the Wideband Networking Platform (WNW) require more affordable, smaller, lighter, and less power consuming hardware if the waveforms are to be used as intended to support present and future tactical operations. Accordingly, there is a need for a method of packaging multiple filters with associated switches and devices compactly in a tactical vehicular radio, so that the radio can support a number of different narrowband and wideband signal waveforms without an increase in physical dimensions or cost.